The present invention relates generally to an apparatus and method to facilitate intramuscular injection of medications in essentially an automatic manner.
Heretofore, intramuscular injections have been accomplished in a rather laborious fashion and were accompanied by inherent limitations and disadvantages from the point of view of the injection recipient as well as that of those administering such injections. Two general methods or cases will be cited to illustrate this point.
In the first method, a sterile needle in a protective sheath is affixed to a sterile glass or plastic syringe, followed by insertion of the needle into a recently disinfected vial or ampule from which the desired medication in specific quantity is drawn in order to ready the syringe for injection. The skin at the injection site is disinfected and ordinarily allowed to dry. The needle is inserted into the tissues at the desired site, ideally without lateral motion, the plunger of the syringe depressed by digital pressure to expel its contents into the tissues following which the needle is withdrawn, again ideally without lateral motion. Although the actual sequence of events may vary depending upon the training and preference of those administering intramuscular injections, the basic method is as described.
In the second method a unit dose cartridge with sterile needle in a protective sheath is positioned in a hinged metal frame, screwed into position, the upper portion of the metal frame swung into position over the vial and locked so that the metal plunger lies above the vial, following which the protective sheath covering the needle is removed. Insertion of the needle into a disinfected injection site is accomplished, ideally without lateral motion, the metal plunger depressed to expel contents of the vial into the tissues, and the needle withdrawn, again, ideally, without lateral motion.
In the first method both the skin and medication container must be disinfected by pads, swabs, sponges or other absorbent materials impregnated with a standard antiseptic or cleansing solution such as an alcohol or Betadine. This may be accomplished by manual impregnation of dry sterile absorbent material or by using prepared impregnated absorbent material individually packed in metal foil tear-open packets. In any event, attention must be given to acquisition and administration of a separate item before an injection may be made. This constitutes a minor inconvenience at best.
Secondly, aseptic technique must be rigidly adhered to in manipulation of the syringe and needle. The needle in its sheath must be carefully affixed to the syringe in a separate manual operation. The needle sheath must be carefully removed, again as a separate portion of the overall procedure. An ampule must be aseptically opened, the needle inserted in an aseptic manner, medication drawn into the syringe in specific quantity -- each as a separate and time-consuming operation prior to injection. In the case of multiple use vials, room air must be drawn into the syringe, the air expelled into the vial, the medication drawn up, and the needle withdrawn from the vial through the hole made in its septum -- again each as time-consuming and inconvenient separate procedures and, as noted, involving acquisition of separate items, viz. ordinarily a disposable needle in its container, a disposable syringe in its container, and medication in ampule or vial form. Regardless of the nature of the container, i.e., either ampule or vial, there is an element of risk involving contamination of the needle or of the medication in its container by microorganisms in the immediate environment or by those which may be present in the air injected in the pressure equalization operation necessary before medication may be withdrawn from a vial.
In the second method a number of the previously noted disadvantages remain as well as development of other objections to be noted below. Again the skin must be disinfected necessitating acquisition and administration of a separate antiseptic-impregnated material. The metal frame of the syringe must be opened for insertion of the cartridge, the latter consisting of a unit dose of medication with an attached sterile needle in a protective sheath. The cartridge must then be rotated clockwise until the needle ferrule is engaged, fixed in a locked position, the open metal frame swung into position and locked, the plunger attached to the threaded end of the piston, the needle sheath removed, the needle inserted into tissue at the injection site, the plunger depressed, the needle removed, the metal frame opened, following which the cartridge is rotated counterclockwise, removed from the metal frame, and discarded -- each as separate procedures.
As will be noted from consideration of the foregoing, both methods are inconvenient, time-consuming, agonizingly slow in emergency procedures, and are accompanied by what will subsequently be seen as largely avoidable risk of infection or sterile abcess formation.
Discussion of the limitations and disadvantages of current intramuscular injection techniques would not be complete without noting the adverse psychological effect on the patient of an exposed hypodermic needle or of a contraption of metal, glass, and exposed needle which bears a strong resemblance to syringes used to inject large animals in veterinary medicine.
The present invention abrogates the foregoing disadvantages by providing an uncomplicated and self-contained apparatus which affords a means of essentially automatic and uniform intramuscular injections, regardless of widely differing abilities to administer such injections.